The present invention relates to an antenna for portable radio sets, and more particularly, to an antenna for portable radio sets in which a reflecting plate is provided for reflecting radiated waves.
In the prior art, a helical antenna and a rod antenna have been combined to form a unitary antenna structure for a portable radio set. With this construction, it is possible to separately operate the helical antenna when the rod antenna is retracted, or to separately operate the rod antenna when the rod antenna is extended.
One prior art reference having both a helical and rod antenna is disclosed in U.S. Pat. No. 4,868,576 entitled Extendable Antenna for Portable Cellular Telephones with Ground Radiator issued to Johnson. In Johnson '576, the rod antenna is positioned on a top portion of a housing and includes two detents which engage tangs of an antenna housing when retracted and extended. The tangs snap into the detents, thereby providing the operator with tactile feedback indicating whether the antenna is fully retracted or extended. The rod antenna slides into and out of the antenna housing, through a helical coil. The rod antenna also includes a protective top end cap, a top portion with the detent, a middle portion with a coil, a bottom portion with the detent and a bottom end cap. The rod antenna is comprised of a flexible plastic material, such as "Delryn" with the mid-portion coil comprised of silver-plated beryllium-copper wire having a diameter of 13 mils (13/1000th of an inch). Therefore, when the rod antenna is retracted, the unit operates as a helical antenna. When extended, the rod antenna is capacitively coupled to the helical antenna. As a result, the configuration is operated in accordance with the length of the rod antenna.
Consequently, the conventional antenna configuration described above distributes centralized radiating power (maximally, 0.6 W) to the helical antenna or the rod antenna. Therefore, a problem results in that harmful electromagnetic waves may be applied to a user's head.